lines:=File("triangle.txt").pump(List,fcn(s){ s.strip().split(" ").apply("toInt") });
d:=lines[-1].copy();
foreach row in ([lines.len()-2..0,-1]){
   d1:=d[1,*];
   l :=d[0];
   foreach i,u in (lines[row].enumerate()){
       d[i] = u + l.max(r:=d1[i]);
       l    = r;
    }
}
println(d[0]);